John Ackerman on Caving
Explore the limestone labyrinth

BY FRANK BURES Published: February 19, 2018

John Ackerman in the upper level of Ackerman’s Cave

PHOTO BY MARTIN LARSEN

Growing up in the Twin Cities, John Ackerman would occasionally venture underground with his high school friends. They would spend hours exploring the old mines in St. Paul and Lilydale, and even once trekked down into the sewers (though toxic sewer gases and seemingly fearless rats limited those excursions). Ackerman loved being underground, wandering the labyrinth.

A few years later, this urge to explore led him to southern Minnesota, where the limestone had never been scraped off by glaciers and where water had carved vast networks underground. There he discovered what would become his life’s passion: caving, which is exactly as it sounds. You enter a cave with lights, ropes, hard hats, and warm clothes to see what’s down there. Ackerman couldn’t get enough. He kept discovering more new caves, and thanks to his successful furniture restoration business, he started buying land around the cave entrances, as well as the “underground rights.”

Throughout Fillmore County (southeast of Rochester) and Iowa, he now owns some 36 miles of caves—which he calls the Minnesota Cave Preserve, and which he plans to preserve for science and exploration. “Caves are like time capsules,” he says. “There’s so much scientific value to them.”

His most noteworthy findings include a 27,000-year-old antler from an extinct moose and a saber-toothed cat skull from the same era. Ackerman also established the Minnesota Caving Club, which has no membership fees and leads expeditions to the Minnesota Cave Preserve nearly every weekend. “We discover waterfalls, rivers, formations, fossils, huge rooms, crevices that are 100 feet deep, and multicolored passages from the minerals that leech through the rocks,” he explains. “The terrain is so different in each cave. It’s just a landscape where you never know what you’re going to see around the next corner.”?